The present invention relates to display systems and, more particularly, to display systems in which magneto-optic chips are used to create a display through Faraday rotation of addressible areas in a beam passing through a polarizer and polarization analyzer.
Magneto-optic displays are a relatively new phenomenon as far as practical adaptations thereof. The magneto-optic chips employed therein are divided into addressible areas, typically in a rectangular pattern. Each area can individually impart Faraday rotation to a light beam passing therethrough in a clockwise or counterclockwise direction. By placing one or more chips between a polarizer on one side and a polarization analyzer on the opposite side, a display pattern can be impressed on a beam of light passing therethrough for projection or direct viewing. The construction and operation of such chips are shown in detail in co-pending applications Ser. No. 320,819, Filed Nov. 12, 1981 by B. E. MacNeal and W. E. Ross, titled ALTERING THE SWITCHING THRESHOLD OF A MAGNETIC MATERIAL and Ser. No. 375,327, Filed on even date herewith by W. E. Ross titled METHOD AND DEVICE FOR INCREASING THE DENSITY OF A PLURALITY OF SWITCHABLE MAGNETIC ELEMENTS both assigned to the assignee of the present invention as are other display applications by the present inventor which are shown in co-pending applications Ser. No. 375,328, titled DYNAMIC MAGNETO-OPTIC SPATIAL FILTERING SYSTEMS, Ser. No. 375,324, titled DIFFUSION-LIGHTED MAGNETO-OPTIC DISPLAY, Ser. No. 375,325, titled MAGNETO-OPTIC DISPLAY, and Ser. No. 375,329, titled IMPROVED MAGNETO-OPTIC IMAGE SCANNING DETECTOR all filed on even date herewith.
In many applications, it is desirable to be able to combine two or more display images in one display device with the ability to switch between them singly or in combination. For example, it would be desirable to be able to view a steady unblinking image on one display while the next updated image for viewing is being invisibly written on another display. This is, of course, possible with two completely individual displays wherein the source of illumination for one is blocked or turned off during such writing. In a single display device, however, such ability, particularly in the form of a memory, is particularly desirable. For example, an oscilloscope used for waveform comparison would be highly desirable if able to maintain the previous waveform which could then be referred to for comparison. When adjusting a tuning slug in an inductance, for example, a band-pass waveform is typically displayed after each adjustment. If newly generated waveforms could be placed alternatively on one display element and then the other, one could always refer back to the previous waveform for comparison. This is a feature, of course, not generally available on a typical cathode ray oscilloscope.
Oscilloscopes, additionally, must be set up for fast response or slow response waveforms. In a fast response waveform, fast phosphors are used which rapidly decay. The display is created by rapidly repeating the scanned waveform. As the moving dot moves across the screen and is deflected, it creates a pattern which is easily recognizable despite the limited persistence of illumination of the phosphors. On the other hand, in a slowly changing environment, slow phosphors with long persistence must be utilized or the overall pattern being created becomes a meaningless slow movement of a single dot across the screen. If such slow phosphors are attempted to be used in a rapid scan pattern, a meaningless jumble of phosphor glow is created. Therefore, it would also be desirable to have a display which could alternate between both modes of operation or, conceivably, combine both into a single display simultaneously.
Wherefore, it is the object of the present invention to provide a display having the aforementioned capabilities.